There are many known methods and devices for coating a moving web and other fixed or moving substrates. For example, a wire-wound rod coater known as a “Mayer Bar” (see U.S. Pat. No. 1,043,021 to Mayer) can be used to make manual hand spreads on small test sheets. Papermaking and paper coating machines have been constructed by including a wire-wound coating rod (sometimes referred to as a “scraper rod”) on one or both sides of the paper web, as shown in Booth, G. L., “The Coating Machine”, Pulp and Paper Manufacture, Vol. 8, Coating, Converting and Processes, pp 76-87 (Third Edition, 1990; see the “Champion Rod Coater” at page 78); Booth, G. L., Evolution of Coating, Vol. 1, (Gorham International Inc.); U.S. Pat. Nos. 1,043,021, 2,229,620, 2,229,621, 2,237,068 and 2,245,045; and at http://www.ferron-magnetic.co.uk/coatings/meterrod.htm. Sometimes the wire-wound coating rod in such machines is slowly rotated during coating, in order to equalize wear on the wire.
Devices for coating substrates of limited length (e.g., small sheets) are also available, and can be used to prepare experimental or test coatings without requiring set up or operation of a web coating apparatus. These typically consist of a knifing apparatus in which a gap is set between a knifing edge and a bed plate, and a sheet is pulled through the gap while it is flooded with coating liquid.